So I am slightly confused about the "Squeal Killer" anti-feedback pedal. It claims to give you 33% more volume before feedback, and it does this with a 12at7 tube inside. Then it also claims that it will only work properly if you have 12ax7 tubes in ALL preamp stages on your amp. My question then is, what is the difference between putting a squeal killer onto an amp with all 12ax7 tubes as opposed to just putting a 12ay7 or 12au7, or heck, even a 12AT7, into the preamp?
On the amps that I have used, putting a 12ay7 or 12au7 in the preamp has already given me at least a 33% increase in volume before feedback. So does adding a squeal killer to an amp with all 12ax7 in the preamp give you 33% more perceived volume on top of what the amp sounds like with a 12ay7? Or does it give you 33% more perceived volume on top of the all 12ax7 (stock) preamp? In which case you might as well just swap out the tubes in the preamp and save yourself $260 plus the hassle of carrying another pedal..
I'm sure I am just confused and there is some advantage to using the pedal. I am just curious what it is. I don't particularly like the idea that my amp will only be useable if I have the Squeal Killer handy though.. ---------- -LeWin$key
Good questions about the Squeal Killer (SK). I own a SK, a Bassman RI, and I have access to a calibrated sound meter at work. But I have never actually measured the differences in dB readings for different combinations of tubes with the SK. This would be a great idea for making a video some Saturday when the family is out of the house (not today).
I have experimented using the SK with all 12AX7's and also with lower gain tubes. I found that the SK worked great with the lower gain tubes as well as the 12AX7's. The SK also works particularly well with my Kalamazoo Model 1, so it has benefits for small amps even though they do not advertise that.
In my experience, plugging into the SK does not give the same result as simply swapping to lower-gain preamp tubes. (I have done quite a lot of experimenting with tube swaps, so I know what those possibilities sound like.) While plugging into the SK does result in a drop in volume of probably a 1 to 1.5 notches on my Bassman volume knob, the SK adds compression, with a punchier attack and a slightly drier, more big-boned tonal quality, while also taming feedback.
For me the advantage of the SK is that I can get the same tone out of the amp that used to come only at the threshold of feedback, only now without the feedback.
I should probably also disclaim that I have a pretty good handle on mic technique, resonance, and tone, so I was already able to get all the volume I needed in performance situations without the SK. But now with the SK, I don't have to worry about the occasional feedback squeal. For reference, even before buying the SK, I was able to comfortably get 113+ dB out my Kalamazoo in my living room with no feedback...don't think I ever measured my Bassman, but I imagine that would be even louder.
The SK take down the strength of the mic signal you send to the guitar amp. It do so without loosing tone and the typical sound you got from overloaded first tube. It cut some hz you don't hear at the same time. The guitar amp works better to a harp because it do not produce distorted overtones as easy as it does with a harmonica hiZ mic. It's not the same as a tube swap. You could only do this directly into a amp if you connect a extra tube the same way as SK is built.
Last Edited by arnenym on Feb 27, 2016 9:10 AM
Changing the gain in your amp via tube substitution is the best way to reduce feedback. You may get 33% or MORE increase ON THE AMP'S VOLUME KNOB but you won't get near that much REAL increase in volume. You WILL be able to play much closer to the feedback threshold because it won't be so quick to leap into feedback. Once again the old throttle pedal analogy: too much gain is like a 500 HP sports car with 1/2" of gas pedal travel. Very hard to use the car's power without going out of control. Reducing gain is like adding 5" of gas pedal travel. Note that you haven't changed idle, and you haven't changed what full throttle is. You have only made it easier to control in between stops. That DOES let you play closer to the feedback threshold while remaining in control so you effectively get some increase in usable volume.
The Squeal Killer does not reduce gain. it reduces the drive level into the amp by cutting your mic's output level by about 10:1. I have measured it on an oscilloscope. Note there is no high voltage power supply - the tube is being used in a strange way, not operating at all like it does when in an amplifier with hundreds of volts of potential across the tube.
The Squeal Killer is a really good, effective solution when you CAN'T reduce the gain of your amp via tube substitute (like when plugging into a borrowed amp or a solid state amp). But if you can, tube subbing is more effective and cheaper. ---------- *************************************************** /Greg
Thanks Greg, that pretty much answers my question. I am pretty happy with my volume level on my amps already just using tube substitutions/good mic technique, so I will probably stick to that and save the dough for now.. And I still can't justify spending the almost $400 on the Kinder pedal but maybe one day i'll cave.. Unless anyones trying to sell one for cheap :D ---------- -LeWin$key
If i understand it correctly, It's reducing the signal of the mic, not reducing volume of the mic.
A VC is still very effective at keeping feedback under control, and Greg's Inline VC'S are the best!
One thing I really like about VC's , is I can turn up the amps volume to its sweet spot, 5-6 so it drives the power tubes and produces the tone I want at lower volumes.
That's how I use them, and with a lower value 100K I get more sweep without effecting tone
Some people keep the amp low and VC high, I think it sounds like crap that way, clean and lifeless.
Sorry, I got OT.
Last Edited by Harpaholic on Feb 27, 2016 2:30 PM
Honestly, you CAN use a VC, turned way down. STILL not as good as re-tubing. And it introduces new problems. First, you're an accidental "whoops turned it up too high" flick away from screaming feedback. Second you've reduced the ability to use the volume control to control YOUR volume. The SK may also actually do some compression though I'm not sure about that. If you have an amp whose feedback you can't deal with through tube subbing, the SK is a good solution.
(And someone will now suggest two volume controls in line. Not a good idea. Too much resistance across your element can suck some tone out. (Volume controls' potentiometers are in fact resistors across the element, and with two they would be in parallel.)
@Greg: I'm still thinking the SK accomplishes something different from tub subs or in-line volume control. Here's how you described it in your post on 2/16/14:
"The Squeal killer attenuates the mic's signal by about 5:1, gently clips the upper half of the wave form, adds about -1V DC shift, cuts highs and boosts bass. None of these are objectionable or severe. Here is a pic of input from my signal generator..."
I'm not an electronics guru, but my impressions were that tube subbing can reduce gain and volume control reduces the signal strength. What you describe above sounds somewhat different from these effects...or I may be misunderstanding, not sure.
I don't pretend to understand the technicalities of how the Squeal Killer works but I have one and it's pretty much eliminated any problems I had previously with feedback. I use it with my Fender Bassman RI LTD with pre-amp tubes 12AX7|12AX7|12AY7. Prior to getting the Squeel Killer I ran 12AX7|12AU7|12AU7.
To my ear the difference is significant. The problem with the lower gain tubes was that I found they muddied the sound of the amp without giving me any significant increase in volume. As the guys have said, I could turn the volume knob further up before feedback, to say 5, but with only similar volume to when I was at 2 with the stock tubes.
With the Squeal Killer using the stock tube configuration I can get to 7 or 8 with a noticeable increase in volume. Also importantly I'm able to bring the Treble up higher (say from 3 to 6) which to my ear adds more punch and allows me to cut through the band better.
Overall I'm really happy with the pedal and use it in every gig. I also have a Harp Train which I use for rehearsals and the pedal also works pretty well for this, even though Jason Lockwood on his website states that his pedal isn't really suited to smaller amps.
I posted a review of the pedal on YouTube if you're interested. Again, nothing technical, just a layman's view:
That was a great explaination greg. The car throttle analogy is pretty good. Thanks
Im wondering why you wouldn't just use the LoneWolf pedal. It's cheaper and plug n play. I'm sure I'm missing something. ---------- "Trust Those Who Seek The Truth. Doubt Those Who Say They Have Found It."
Last Edited by Killa_Hertz on Feb 28, 2016 5:14 AM
Adam, that was a great demo, but the only thing missing is a decibel meter which would produce more scientific results giiving us a better idea of before and after volumes.
There are dozens of Db meter apps available for iPhone and Android.
Killa_hertz, if i'm not mistaken the Lone Wolf pedal is essentially just a noise gate. It is not going to give you more volume, just make it so your amp won't feedback in between playing, which is pretty much what I use my VC for.. ---------- -LeWin$key
@Killa: The Lone wolf pedal doesn't work the same way. It does not reduce the mic's signal, or do any EQ or compression. It is a "noise gate" that mutes the mic input when the signal level falls below a certain point. ---------- *************************************************** /Greg
I realise how it works. I have one. I guess what i ment was, Cant you crank your amp up to the feedback threshold your after and use the LW pedal to eliminate feedback?
I guess i should look into how the SK works.
But it seems like there are easier ways to get the same result. I could be wrong. I was just wondering. ---------- "Trust Those Who Seek The Truth. Doubt Those Who Say They Have Found It."
Last Edited by Killa_Hertz on Feb 28, 2016 10:27 AM
Personally, I find that using preamp tubes lower in gain than AT's in any position other than the phase inverter makes my amps sound wimpy. IMHO, using a SK helps control feedback without sacrificing tone like you do using AUs or AYs for preamp tubes. But, YMMV. I only use my SK for predictably high volume gigs.
Last Edited by hvyj on Feb 28, 2016 7:50 PM
I guess it depends on the amp. I've never noticed a detrimental tone change with tube swaps, even going to 12AU's. @Killa -the LW pedal won't do anything about the gain structure of the amp, so as soon as you start to play you're still going to have knife-edge feedback that's hard to control. ---------- *************************************************** /Greg
@Greg: It may be the mic/amp combination. I don't use bullet mics or harp specific amps. These days I use the hi-z and lo-z 545 Ultimates I got from you pretty much exclusively, but occasionally I'll use an Audix D-1 snare drum mic with one of your in line VCs on it. (I like it better than the Fireball.) Anyway, if I try 12AU7s in my SRRI or PRRI guitar amps with any of these mics, the amps sound dull and lifeless. JJ now makes a 12AY7 but come to think of it, I haven't actually tried one of those. But the AUs just don't work very well for me. Maybe it has to do with the smaller coupling caps in the guitar amps. But I dunno. I'm just speculating.
I've got AT7 D/W7 AT7 in that order in the preamp section of my Peavey Delta Blues which sounds very good, but I've never tried an AU7 or AY7 in that amp. The DB gets louder before feedback than my SRRI. And with the SK it can get even louder. I like the SK for its simplicity. Just plug and play. Nothing you need to dial in except the tone controls on the amp and the VCs on the mic and amp.
Last Edited by hvyj on Mar 01, 2016 9:57 AM
@hvjy - 100% agreement - the SK is butt-simple - plug it in, hook it up, it works. For that reason it has earned a spot in my kit. I rarely have to use it but I know there will come a day when i need it and I will be damn glad to have it. ---------- *************************************************** /Greg
Greg, as usual, provides accurate and knowledgeable information. Anti-feedback devices of whatever description are very useful for taming amps that have been handed to you to use as is. Tube swaps are usually the first order of the day when modifying guitar amps in ones possession for harp. I've had dozens of amps that I have swapped out tubes for something of lower gain. I've never had a problem with tone being affected provided quality tubes are used. ---------- LSC ---------- LSC
